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New Post: Transpose a vector

July 16, 2014, 5:17 am
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thank you for the help and the great explanation,
really fast and informative.
Thank you,
michael
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New Post: Step function/interpolator

July 16, 2014, 5:33 am
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I implemented a piece wise constant interpolator. would you like to have it?
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New Post: Transpose a vector

July 16, 2014, 5:36 am
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by the way, could you please help me with a matrix access?
How could i do this matlab syntax?
Mnew = M (:,2)
or
Mnew = M(3,3:6)

do have experiences here also?

michael
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New Post: Transpose a vector

July 16, 2014, 12:04 pm
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You can use the SubMatrix() method to extract contiguous slices.
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New Post: Transpose a vector

July 17, 2014, 1:00 am
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New Post: Issues with f# sample code

July 18, 2014, 4:05 pm
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Hi all,
I'm attempting to run this sample code copied from http://numerics.mathdotnet.com/docs/ in the VS interactive window. The code returns the following error:
The type referenced through 'MathNet.Numerics.LinearAlgebra.Matrix`1' is defined in an assembly that is not referenced. You must add a reference to assembly 'MathNet.Numerics'.
Any thoughts on what is going wrong? The dlls were acquired through nuget. They are version 3.0.2.
#r @"C:\path_to_dlls\MathNet.Numerics.dll"
#r @"C:\path_to_dlls\Mathnet.Numerics.FSharp.dll"
open MathNet.Numerics
open MathNet.Numerics.LinearAlgebra
open MathNet.Numerics.LinearAlgebra.Double
SpecialFunctions.Gamma(0.5)

let m : Matrix<float> = DenseMatrix.randomStandard 50 50
(m * m.Transpose()).Determinant()
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New Post: How to apply operation over vector from each row/column of a matrix?

July 19, 2014, 12:41 pm
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I have been porting some code that I had with my own Matrix<T> implementation but Math.Net is far more complete.

And I am wondering if there exists such a method here.
My code looked like this:

wu_v += Functions.Sum(v, Axis.Rows);

Where wu_v is a Matrix<T> and v is a Vector<T>. The alternative is to do:
wu_v = wu_v + ones * diag(v) or coding it by hand for performance, but I was wondering if there was such a construct already.

Federico
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New Post: How to apply operation over vector from each row/column of a matrix?

July 20, 2014, 2:06 am
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Hi Federico,

I don't fully understand yet what the operation should do. What does Functions.Sum(v, Axis.Rows) do and how does it relate to ones * diag(v), exactly?

Maybe you're looking for FoldRows(f,state) which applies a binary function to each row vector of the matrix and a state vector (where the result becomes the state for the next row)? See also "Enumerators and Higher Order Functions" in Matrices and Vectors.

Thanks,
Christoph
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New Post: Issues with f# sample code

July 20, 2014, 2:16 am
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The NuGet package contains builds for multiple platforms. Which one did you reference? Sounds a bit as if the .Net 3.5 assemblies had been referenced.

Thanks,
Christoph
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New Post: Step function/interpolator

July 20, 2014, 6:09 am
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Great, thanks! I've cherry-picked the step but also the log-linear and transformed intepolators to mainline.

Thanks,
Christoph
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New Post: Compiler error calling MathNet Numerics DelimitedWriter.WriteFile

July 20, 2014, 9:41 am
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Created Release: Math.NET Numerics v3.1.0 (Jul 20, 2014)

July 20, 2014, 11:25 am
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  • Random: generate a sequence of integers within a range in one go
  • Distributions: all distributions must have static routines to sample an array in one go
  • Linear Algebra: fix Matrix.StrictlyLowerTriangle
  • Linear Algebra: fix vector DoOuterProduct ~mjmckp
  • Linear Algebra: enumerators accept Zeros-parameter (like map/fold already does)
  • Linear Algebra: Vector.MapConvert (consistency)
  • Linear Algebra: proper term for 'conjugate symmetric' is 'Hermitian'
  • Interpolation: new Step, LogLinear and transformed interpolators ~Candy Chiu
  • Interpolation: check for min required number of data points, throw ArgumentException if not.
  • Root Finding: F# FindRoots.broyden module function ~teramonagi
  • Misc docs fixes
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Released: Math.NET Numerics v3.1.0 (Jul 20, 2014)

July 20, 2014, 11:28 am
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  • Random: generate a sequence of integers within a range in one go
  • Distributions: all distributions must have static routines to sample an array in one go
  • Linear Algebra: fix Matrix.StrictlyLowerTriangle
  • Linear Algebra: fix vector DoOuterProduct ~mjmckp
  • Linear Algebra: enumerators accept Zeros-parameter (like map/fold already does)
  • Linear Algebra: Vector.MapConvert (consistency)
  • Linear Algebra: proper term for 'conjugate symmetric' is 'Hermitian'
  • Interpolation: new Step, LogLinear and transformed interpolators ~Candy Chiu
  • Interpolation: check for min required number of data points, throw ArgumentException if not.
  • Root Finding: F# FindRoots.broyden module function ~teramonagi
  • Misc docs fixes

3.0.2 - 2014-06-26:
  • Patch release, fixing a bug in Matrix.RemoveRow range checks.

3.0.1 - 2014-06-24:
  • Patch release, fixing a bug in new Matrix.ToMatrixString and Vector.ToVectorString routines.
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Updated Release: Math.NET Numerics v3.1.0 (Jul 20, 2014)

July 20, 2014, 11:28 am
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  • Random: generate a sequence of integers within a range in one go
  • Distributions: all distributions must have static routines to sample an array in one go
  • Linear Algebra: fix Matrix.StrictlyLowerTriangle
  • Linear Algebra: fix vector DoOuterProduct ~mjmckp
  • Linear Algebra: enumerators accept Zeros-parameter (like map/fold already does)
  • Linear Algebra: Vector.MapConvert (consistency)
  • Linear Algebra: proper term for 'conjugate symmetric' is 'Hermitian'
  • Interpolation: new Step, LogLinear and transformed interpolators ~Candy Chiu
  • Interpolation: check for min required number of data points, throw ArgumentException if not.
  • Root Finding: F# FindRoots.broyden module function ~teramonagi
  • Misc docs fixes

3.0.2 - 2014-06-26:
  • Patch release, fixing a bug in Matrix.RemoveRow range checks.

3.0.1 - 2014-06-24:
  • Patch release, fixing a bug in new Matrix.ToMatrixString and Vector.ToVectorString routines.
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New Post: How to apply operation over vector from each row/column of a matrix?

July 20, 2014, 2:22 pm
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Probably FoldRows(f,state) is what I need to build it.

Function.Sum(v, Axis.Rows) looks like this (column-major):
 for (int majorItem = 0; majorItem < t.Length; majorItem++)
 {
     for (int i = 0; i < items; i++)
          t[majorItem] += mt[ptr + i * minorStride];

     ptr += majorStride;
 }
It treats every column of the matrix M as a vector mv and adds the vector v to it.
For every k in M
     mv = M.GetColumnVector(k);
     mv += v ;
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New Post: How to apply operation over vector from each row/column of a matrix?

July 20, 2014, 3:00 pm
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Ah, that looks more like:
m.MapIndexedInplace((i,j,x) => x + v.At(i));
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New Post: How to apply operation over vector from each row/column of a matrix?

July 20, 2014, 5:42 pm
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This is the implementation. Is there any way to avoid the casting?
 public static Matrix<T> AddVectorOnEachColumn<T>(this Matrix<T> m1, Vector<T> v, T scale) where T : struct, 
                                                                                                     IEquatable<T>, IFormattable
 {
     Contract.Requires(m1 != null);
     Contract.Requires(v != null);
 
     if (m1 is Matrix<float>)
     {
         var fm1 = m1 as Matrix<float>;
         var fv = v as Vector<float>;
         var fscale = (float)(object)scale;
 
         return fm1.MapIndexed((i, j, value) => fm1.At(i, j) + fscale * fv.At(j)) as Matrix<T>;
     }
     else if (m1 is Matrix<double>)
     {
         var dm1 = m1 as Matrix<double>;
         var dv = v as Vector<double>;
         var dscale = (double)(object)scale;
 
         return dm1.MapIndexed((i, j, value) => dm1.At(i, j) + dscale * dv.At(j)) as Matrix<T>;
     }
     else throw new NotSupportedException("Type: {0} is not supported by the Matrix<T> class.");
 }
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New Post: How to apply operation over vector from each row/column of a matrix?

July 20, 2014, 11:19 pm
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dm1.At(i, j) is already provided as value:
fm1.MapIndexed((i, j, value) => value + fscale * fv.At(j)) as Matrix<T>
Then you can pre-scale the vector, once, which is supported generically; getting rid of some of the casting:
var fm1 = m1 as Matrix<float>;
var fsv = (v * scale) as Vector<float>;
return fm1.MapIndexed((i, j, value) => value + fsv.At(j)) as Matrix<T>;
Do you actually need the extension function to be generic? If not, you can just overload per type individually, without any casting:
// Inplace:
public static void AddScaledVectorToEachColumnInplace(this Matrix<double> m, Vector<double> v, double scale)
{
    double[] scaled = (v * scale).ToArray();
    m.MapIndexedInplace((i,j,x) => x + scaled[i], Zeros.Include);
}
public static void AddScaledVectorToEachColumnInplace(this Matrix<float> m, Vector<float> v, float scale)
{
    float[] scaled = (v * scale).ToArray();
    m.MapIndexedInplace((i,j,x) => x + scaled[i], Zeros.Include);
}

// Outplace:
public static Matrix<double> AddScaledVectorToEachColumn(this Matrix<double> m, Vector<double> v, double scale)
{
    double[] scaled = (v * scale).ToArray();
    return m.MapIndexed((i,j,x) => x + scaled[i], Zeros.Include);
}
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New Post: Step function/interpolator

July 23, 2014, 8:02 am
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Christoph,

I am not sure if you saw my alternative implementation of LeftBracketIndex which uses Array.BinarySearch. I'd recommend adopting it at other places.

Candy
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New Post: Sparse matrix performance

July 23, 2014, 11:54 am
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Thanks again. I've included the change and extended it to the writer as well. Since dense matrices are stored in column-major format it was possible to optimize the dense case slightly as well, along the same lines. Available in the MathNet.Numerics.Data.Matlab v3.0.0 package.

Thanks,
Christoph
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